1. Field of the Invention
The present invention relates to a light source and an original reading device, and in particular, to a light source which is formed by connecting terminals of a plurality of light emitting elements to predetermined positions of a wiring pattern formed in advance on a substrate, and to an original reading device which irradiates light onto an original and reads the transmitted image or the reflected image by light converting elements.
2. Description of the Related Art
In recent years, original reading devices have been realized in which illumination light is irradiated onto an original such as a photographic film, and the reflected or transmitted light, which includes image information of the image recorded on the original, from the original is received by a CCD (charge coupled device) such that the image recorded on the original is read. Processings such as various types of correction are carried out on the image data obtained by the reading. Thereafter, the image is recorded onto a recording material such as a photographic printing paper, or the image is displayed on a display. Such an original reading device is advantageous in that it is easy to make automatic the operations from the reading of an image recorded on an original to the recording of the image onto a recording material such as a photographic printing paper.
In the original reading device described above, conventionally, a white light source such as a halogen lamp or the like has been used as the light source for illuminating the original. However, in recent years, devices have been realized in which, instead of a white light source, an LED light source is used. The LED light source is structured by a plurality of LED elements, which emit colors of RGB (IR (infrared) light can also be emitted in order to detect positions of scratches), being arrayed on a substrate.
By using an LED light source, filters for color separation of the light emitted from the white light source can be eliminated, thus making the structure of the device more simple. Further, setting of the conditions, such as the respective color balances and the like, can be simplified.
Because the amount of output light of an LED light source is generally lower than that of a halogen lamp, the light must be used efficiently. However, light emitted from the respective LED elements of the LED light source is also emitted in directions other than toward the original (some of the light is not emitted toward the original). For example, because the surface of the substrate is generally a color having low reflectance (e.g., a dark green color), light emitted toward the surface of the substrate at which the LED elements are mounted cannot be used as light for illuminating the original, and the efficiency of utilizing the light is poor.
Further, the LED elements are arrayed on the substrate at predetermined pitches. Thus, as opposed to a light source having continuous light emitting points, the distribution of the amount of light illuminated toward the surface of the original is not uniform (known as non-uniformity of the light amount), and thus, a problem arises in that non-uniform density is exhibited in the read image.
Attempts have been made to eliminate this non-uniformity of the light amount by providing a diffusion plate on the optical path. However, the amount of light is reduced due to the diffusion plate, and even more LED elements must be provided in order to obtain the amount of light needed, which leads to an increase in the number of parts.
Further, the LED elements on the substrate of the LED light source break easily due to shocks or the like. Even if only one LED elements breaks, the entire LED light source must be replaced, which results in the problem of high operating costs.
The present invention was developed in order to overcome the above-described drawbacks, and an object of the present invention is to provide a light source and an original reading device which can emit light uniformly with a low loss of light and with the minimum number of light emitting elements necessary, and in which breaking of light emitting elements on a substrate can be prevented.
In order to achieve the above object, a first aspect of the present invention is a light source structured by a plurality of light-emitting elements being connected to predetermined positions of a wiring pattern formed in advance on a substrate, the light source comprising: a reflecting member provided at a position of the substrate other than positions at which the plurality of light-emitting elements are disposed on the substrate, the reflecting member having a reflectance which is higher than a reflectance of the substrate.
In accordance with the first aspect of the present invention, the reflecting member is provided on the substrate on which the light emitting elements (LEDs, ELs or the like) are disposed such that the reflecting member is not disposed at positions at which the light emitting elements are disposed. (Namely, the reflecting member is disposed at a predetermined position of the substrate, which is other than the positions at which the light emitting elements are disposed.) As a result, the light emitted from the light emitting elements backward (toward the substrate) is reflected forward by the reflecting member. The reflectance of the reflecting member is higher than the reflectance of the substrate. Thus, more light can be reflected forward as compared with a case in which no reflecting member is provided. Together with the direct light emitted directly forward from the light emitting elements, the large amount of reflected light which is reflected by the reflecting member can also be used as effective light source light. The efficiency of light use can thereby be improved.
In a second aspect of the present invention, in the first aspect, the reflecting member is a film which is of a substantially white color and which protects a surface of the substrate.
In a third aspect of the present invention, in the first aspect, the reflecting member is a reflective plate which is provided on the substrate.
The reflecting member may be, as in the second aspect, a substantially white (i.e., a color having a high reflectance) resist film for protecting the surface of the substrate (a corrosion-resistance protective film provided on the surface of the substrate for preventing the wiring on the substrate from being corroded due to oxidation or the like). Or, as in the third aspect, the reflecting member may be a reflecting plate (which is adhered onto the substrate).
A fourth aspect of the present invention is a light source structured by a plurality of light-emitting elements being connected to predetermined positions of a wiring pattern formed in advance on a substrate, wherein a surface of the substrate on which the light-emitting elements are disposed is substantially white.
In a fifth aspect of the present invention, in the fourth aspect, the substrate is a ceramic substrate.
In accordance with the fourth aspect, a substrate is used whose surface, on which light emitting elements (LEDs, ELs or the like) are disposed, is substantially white (i.e., a color having high reflectance). In this way, the light emitted backward (toward the substrate) from the light emitting elements is reflected forward. For example, as in the fifth aspect, a ceramic substrate may be used as the substrate on which the light emitting elements are provided.
In this way, in the same way as in the first aspect, together with the direct light emitted from the light emitting elements directly forward, the large amount of reflected light reflected by the substrate surface on which the light emitting elements are provided can be used as effective light source light. Thus, the efficiency of utilization of light can be improved.
In a sixth aspect of the present invention, the light source of any of the first through third aspects further comprises a tube-shaped light collecting member which is provided at a surface side of the substrate at which the light-emitting elements are disposed, and which encompasses the substrate, and whose inner peripheral surface is a reflection diffusion surface having a reflectance of substantially 100% and a diffuse reflectance of substantially 100%.
In accordance with the sixth aspect of the present invention, the tube-shaped light collecting member is provided at the surface side of the substrate on which the light emitting elements are provided. More specifically, the light collecting member stands upright at the periphery of the substrate so as to encompass the substrate. A reflecting diffusing surface is formed at the inner peripheral surface of the light collecting member. In this way, the light emitted from the light emitting elements (the light including the direct light and the reflected light) is diffused and reflected by the reflecting diffusing surface. Thus, light can be collected in a desired direction and the light amount distribution of the collected light can be made uniform (i.e., non-uniformity of the light amount can be suppressed) without a loss in the amount of light.
A seventh aspect of the present invention is a light source structured by a plurality of light-emitting elements being connected to predetermined positions of a wiring pattern formed in advance on a substrate, wherein the substrate has at least one recess portion which is formed to be deeper than a heightwise dimension of the light emitting element, and at least one light emitting element is disposed in the recess portion.
In an eighth aspect of the present invention, the light source of the seventh aspect further comprises a protective resin layer which is insulative and covers at least the light emitting element within the recess.
In accordance with the seventh aspect of the present invention, the light emitting element(s) is (are) disposed in the recess portion(s) which is (are) deeper than the heightwise dimension of the light emitting element(s). Thus, breaking of the light emitting elements can be prevented.
At this time, if a protective resin layer such as that of the eight aspect of the present invention is provided in the recess portion, the moisture-resistance of the light emitting elements and the wires can be improved, and corrosion of the light emitting elements and the wires and the like on the substrate can be prevented.
A ninth aspect of the present invention is a light source structured by a plurality of light-emitting elements being connected to predetermined positions of a wiring pattern formed in advance on a substrate, the light source comprising: a protective resin layer which is insulative and covers one of a portion of and all of a surface of the substrate so as to cover at least the light emitting elements.
In accordance with the ninth aspect of the present invention, a portion of or all of the substrate surface is covered by the protective resin layer such that at least the light emitting elements are covered. Thus, breakage of the light emitting elements can be prevented, and corrosion of the light emitting elements and the wires and the like can be prevented.
In a tenth aspect of the present invention, in the eighth aspect, the protective resin layer is a milky-white color.
As in the tenth aspect of the present invention, if the protective resin layer is a milky white color, non-uniformity of the light amount can be suppressed even more.
In an eleventh aspect of the present invention, in any of the first through tenth aspects, the substrate is divided into plural divisional regions, and on/off control of the light emitting elements disposed in the divisional regions can be carried out per divisional region.
In accordance with the eleventh aspect, the substrate is divided into a plurality of regions, and for each of the divisional regions, the light emitting elements disposed therein can be on/off controlled independently of the light emitting elements of the other divisional regions. Namely, it is possible to turn the light emitting elements of only desired divisional region(s) on and off (i.e., it is possible to make only the light emitting elements disposed in a desired divisional region(s) emit light/not emit light). In this way, for example, control can be carried out such that, in accordance with the amount of light needed as the light source, the number of divisional regions which are turned on is varied and light of an amount greater than that needed is not outputted. This results in energy conservation. Further, light can be outputted by switching the on/off states of the divisional regions per each short period of time (i.e., pulse lighting can be carried out), such that the life of the light source can be extended.
In a twelfth aspect of the present invention, in any of the first through tenth aspect of the present invention, the substrate is structured by combining a plurality of secondary substrates, and on/off control of the light emitting elements disposed on the secondary substrates can be carried out per secondary substrate.
In accordance with the twelfth aspect of the present invention, the substrate is structured by combining a plurality of secondary substrates. For each of the secondary substrates, the light emitting elements disposed thereon can be on/off controlled independently of the light emitting elements of the other secondary substrates. Thus, for example, a light source manufacturer can manufacture light sources in units of small secondary substrates, rather than in the conventional units of large substrates, leading to a lowering of the production cost of the light source. Further, if there are problems with some of the light emitting elements, such as elements have expired or have been broken, conventionally, there was the need to replace the entire large substrate. However, in accordance with the present invention, it suffices to replace only the small secondary substrate on which the problematic light emitting elements are disposed.
In a thirteenth aspect of the present invention, in any of the first through the twelfth aspects, the plurality of light-emitting elements are different types of light emitting elements which output lights of respectively different wavelength bands, and on/off control of the light emitting elements of the different types can be carried out per type.
In accordance with the thirteenth aspect of the present invention, light emitting elements of different types which emit light of different wavelength bands (such as R, G, and B) are on/off controlled per type. In this way, the outputting of light can be switched between R, G, and B lights. For example, it is possible to output only R light from the light source, or to output R, G and B lights simultaneously.
In a fourteenth aspect of the present invention, in any of the first through thirteenth aspects, the light emitting elements are formed from plural circuits which are each formed from plural light emitting elements connected in series, the plural circuits are disposed in parallel on the basis of a predetermined pattern, and (simultaneously) on/off control of the light emitting elements of the circuits can be carried out per circuit.
In accordance with the fourteenth aspect, a plurality of circuits, in each of which a plurality of light emitting elements are connected in series, are disposed parallel to one another (are parallel connected). On/off control can be carried out for each of the circuits. In this way, for example, if a problem arises in a light emitting element of any of the circuits, such as the light emitting element is no longer able to emit light, the effect of that problem is limited to that circuit. By controlling the other circuits, which are parallel connected, in consideration of the problematic circuit, the light source can function effectively by use of the light emitting elements of only these other circuits.
The number of light emitting elements which are turned on can be controlled in accordance with the number of circuits which are on. Thus, adjustment of the output light amount-can be carried out easily. Further, if the light emitting elements of the series connected circuit are the same type of light emitting elements, by carrying out on/off control on a circuit-by-circuit basis, on-off control can be carried out per type of light emitting element. Thus, the adjustment of the light amount balance (the color balance) can also be carried out easily.
The fifteenth aspect of the present invention is an original reading device comprising the light source of any of the first through fourteenth aspects, wherein light from the light source is illuminated onto an original, and one of a transmitted image and a reflected image is read by photoelectric converting elements.
In accordance with the fifteenth aspect, the invention of any of the first through fourteenth aspects is used as a light source for illuminating light onto an original.
For example, if the invention of any of the first through fifth aspects is used, due to the reflecting member or the substantially white substrate surface, a greater amount of light is reflected toward the original and light can be utilized more efficiently. Thus, the light amount needed for reading of an original can be obtained even if the number of light emitting elements it not increased, i.e., with a number of light emitting elements which is smaller than the number used conventionally.
If the invention of the sixth aspect is applied, the light emitted from the light emitting elements (the direct light and reflected light) is diffused and reflected by the inner peripheral surface of the light collecting member, such that the light amount distribution is made uniform. Accordingly, light can be illuminated uniformly onto the original, and highly precise (i.e., with little non-uniformity of density) reading of an original is possible.
Further, if the invention of any of the seventh through ninth aspects is applied, breakage of the light emitting elements and corrosion of the light emitting elements or the wires can be prevented. Thus, the light source can be changed less frequently, which leads to a reduction in operating costs. Moreover, if the invention of the tenth aspect is applied, the light amount distribution of the light (direct light and reflected light) illuminated onto the original is made uniform. Accordingly, light can be illuminated uniformly onto the original, and highly precise (i.e., with little non-uniformity of density) reading of an original is possible.
If the invention of the eleventh aspect is applied, on/off control of the light emitting elements is carried out per divisional region of the divided substrate. Thus, for example, the number of divisional regions which are turned on can be varied, in accordance with the type of the original or with the density of the recorded image, such that light is not outputted in an amount which is greater than needed. Thus, energy can be conserved. Further, for example, light can be outputted by switching the on/off state of the divisional regions per short period of time (i.e., pulse lighting can be carried out) such that the life of the light source can be extended. In this way, the light source can be changed less frequently, which results in a reduction in operating costs.
If the invention of the twelfth aspect is applied, the light emitting elements can be on/off controlled per secondary substrate forming the substrate. Because the light source is manufactured in units of secondary substrates (For example, the structures of the secondary substrates are the same.), the production cost can be reduced. Further, if there are problems with some of the light emitting elements, such as elements have expired or have been broken, conventionally, there was the need to replace the entire large substrate. However, in accordance with the present invention, it suffices to replace only the small secondary substrate on which the problematic light emitting elements are disposed. Thus, the operating costs can be reduced.
If the invention of the thirteenth aspect is applied, on/off control of the light emitting elements is carried out per type of the light emitting elements which emit light of different wavelength bands such as R, G, and B. Thus, light can be illuminated by switching between R, G and B lights, or only R light can be illuminated onto the original, or lights of R, G and B can be illumined simultaneously.
If the invention of the fourteenth aspect is applied, on/off control can be carried out on a circuit-by-circuit basis, where each circuit is formed by light emitting elements being connected in series. Thus, for example, even if a problems arise in one of the light emitting elements within a circuit such as the light emitting element is no longer able to emit light, the effect thereof is limited to that circuit. By controlling the other circuits which are connected in parallel, the function of the light source can be realized and reading of the original can be carried out even if only these other circuits are used.
Further, adjustment of the amount output light of the light source is easy. Thus, adjustment of the amount of light illuminated onto the original is also easy. Moreover, the light emitting elements of the series connected circuit are light emitting elements of the same type, by effecting on/off control on a circuit-by-circuit basis, on/off control per type of light emitting element is made possible. Thus, adjustment of the light amount balance (color balance) of the light illuminated onto the original is also easy.